Transfer of azo dyes having a pyridine coupling component

ABSTRACT

Azo dyes are transferred from a substrate to a plastic-coated paper by diffusion with the aid of a thermal printing head, these azo dyes having the formula ##STR1## where D is the radical of a diazo component and 
     R 1 , R 2  and R 3  are each independently of the others hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted phenyl or substituted or unsubstituted cyclohexyl and 
     R 4  is alkyl.

The present invention relates to a novel process for transferring azo dyes having a diaminopyridine-based coupling component from a substrate to a plastic-coated paper with the aid of a thermal printing head.

In thermotransfer printing processes, a transfer sheet which contains a thermally transferable dye in one or more binders with or without suitable assistants on a substrate is heated from the back with a thermal printing head in short heat pulses (duration: fractions of a second), as a result of which the dye migrates out of the transfer sheet and diffuses into the surface coating of a receiving medium. The essential advantage of this process is that control of the amount of dye to be transferred (and hence of the color gradation) is easily possible by adjusting the energy to be supplied to the thermal printing head.

In general, color recording is carried out using the three subtractive primaries yellow, magenta and cyan (and in certain cases black). To facilitate optimal color recording, the dyes must have the following properties:

(i) ready thermal transferability,

(ii) low migration tendency within or on the surface coating of the receiving medium at room temperature,

(iii) high thermal and photochemical stability and resistance to moisture and chemical substances,

(iv) suitable hues for subtractive color mixing,

(v) a high molar adsorption coefficient,

(vi) resistance to crystallization in the course of storage of the transfer sheet and

(vii) ready industrial accessibility.

These requirements are from experience very difficult to meet at one and the same time.

For this reason most of the known cyan dyes used for thermal transfer printing do not meet the required range of properties.

There is prior art concerning dyes used in thermotransfer printing processes. For instance, EP-A-216,483 and EP-A-258,856 describe azo dyes from thiophene-based diazo components and aniline-based coupling components.

Furthermore, EP-A-218,397 describes thiophene- and aniline-based disazo dyes for this purpose.

JP-A-30,392/1985 teaches the use of azo dyes which have a diazo component based on 5-aminothia-2,4-diazole and a coupling component based on aniline.

Finally, JP-A-227,092/1986 discloses the used of azo dyes whose diazo and coupling components come from the aniline series.

It is an object of the present invention to provide a process for the transfer of dyes where the dyes should ideally meet all the abovementioned requirements (i) to (vii).

We have found that this object is achieved in an advantageous manner by transferring azo dyes from a substrate to a plastic-coated paper by diffusion with the aid of a thermal printing head on using a substrate on which there are one or more azo dyes of the formula I ##STR2## where

R¹, R² and R³ are identical or different and each is independently of the others alkyl, alkoxyalkyl, alkanoyloxyalkyl, alkoxycarbonyloxyalkyl or alkoxycarbonylalkyl, which each may have up to 20 carbon atoms and be substituted by phenyl, C₁ -C₄ -alkylphenyl, C₁ -C₄ -alkoxyphenyl, halophenyl, benzyloxy, C₁ -C₄ -alkylbenzyloxy, C₁ -C₄ -alkoxybenzyloxy, halobenzyloxy, halogen, hydroxyl or cyano, or are each hydrogen, unsubstituted or C₁ -C₁₅ -alkyl-, C₁ -C₁₅ -alkoxy-, halogen- or benzyloxy-substituted phenyl, unsubstituted or C₁ -C₁₅ -alkyl-, C₁ -C₁₅ -alkoxy, halo- gen- or benzyloxy-substituted cyclohexyl or a radical of the formula II

    [--Y--O].sub.m --R.sup.5 8c                                (II)

where 3

Y is C₂ -C₆ -alkylene,

m is 1, 2, 3, 4, 5, or 6 and

R⁵ is C₁ -C₄ -alkyl or unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄ -alkoxy-substituted phenyl,

R⁴ is C₁ -C₄ -alkyl and

D is the radical of a diazo component.

The radical D in the formula I is derived for example from a diazo component which comes from the aniline, phenylazoanline, aminothiophene, phenylazoaminothiophene, aminothiazole, phenylazoaminothiazole, aminoisothiazole or aminothiadiazole series.

Preference is given to the use of dyes of the formula I where the radical D is derived for example from a diazo component D-NH₂ of the formula ##STR3## where

R⁷, R⁸ and R⁹ are identical or different and each is independently of the others alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, which may each have up to 12 carbon atoms, hydrogen, cyano, halogen, nitro, or a radical of the formula II

    [--Y--O].sub.m R.sup.5                                     (II),

where Y, R⁵ and m are each as defined above, or a radical of the formula --CO--OR¹⁷, --CO--NR¹⁷ R¹⁸, --SO₂ --R¹⁷, --SO₂ --OR¹⁷ or --SO₂ --NR¹⁷ R¹⁸, where R¹⁷ and R¹⁸ are identical or different and each is independently of the other alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, which may each have up to 12 carbon atoms, hydrogen or a radical of the formula II

    [--Y--O].sub.m --R.sup.5 (II),

where Y, R⁵ and m are each as defined above,

R¹⁰ is hydrogen, chlorine, cyano, C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, C₁ -C₈ -alkylthio, alkoxyalkyl of up to 8 carbon atoms, phenyl, which may be substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or benzyloxy, benzyl, benzyloxy or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above,

R¹¹ is hydrogen, cyano, nitro or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above,

R¹² is cyano, nitro, formyl or a radical of the formula ##STR4## where

R¹⁷ and R¹⁸ are each as defined above,

R¹³ R¹⁴ are identical or different and each is independently of the other hydrogen, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, chlorine, cyano, nitro or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above,

R¹⁵ is hydrogen, C₁ -C₄ -alkyl or chlorine, and

R¹⁶ is cyano or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁶ where R¹⁷ and R¹⁸ are each as defined above.

Any alkyl in the abovementioned formula can be linear or branched.

Y is for example ethylene, 1,2-or 1,3-propylene, 1,2-, 1,3- 1,4- or 2,3-butylene, pentamethylene, hexamethylene or 2-methylpentamethylene.

R¹, R², R³, R⁴, R⁵, R⁷, R⁸, R⁹, R¹⁰, R¹³, R¹⁴, R¹⁵, R¹⁷ and R¹⁸ are each for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl or tert-butyl.

R¹, R², R³, R⁷, R⁸, R⁹, R¹⁰, R¹⁷ and R¹⁸ are each further for example pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-ethylhexyl or isooctyl.

R¹, R², R³, R⁷, R⁸, R⁹, R¹⁷ and R¹⁸ are each further for example nonyl, isononyl, decyl, isodecyl, undecyl or dodecyl.

R¹, R² and R³ are each further for example tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl or eicosyl. (The terms isooctyl, isononyl, isodecyl and isotridecyl are trivial names due to alcohols obtained by the oxo process (cf. Ullmanns Enzyklopadie der technischen Chemie, 4th edition, volume 7, pages 215-217 and volume 11, pages 435 and 436).)

R¹, R², R³, R⁷, R⁸, R⁹, R¹⁷ and R¹⁸ are each further for example 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 2- or 3-ethoxpropyl, 2- or 3-propoxypropyl, 2- or 3-butoxypropoyl, 4-methoxybutyl, 4-ethoxybutyl, 4-butoxybutyl, 4-(2-ethylhexyloxy)butyl, 8-methoxyoctyl or 8-butoxyoctyl.

R¹⁰, R¹³ and R¹⁴ are each further for example methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy or sec-butoxy.

R¹⁰ is further for example pentyloxy, isopentyloxy, neopentyloxy, hexyloxy, heptyloxy, octyloxy, 2-ethylhexyloxy, methylthio, ethylthio, propylthio, isopropylthio, butylithio, pentylthio, hexylthio, heptylthio, octylthio or 2-ethylhexylthio.

R¹, R² and R³ are each further for example benzyl, 1-or 2-phenylethyl, ##STR5##

The radicals R⁷, R⁸, R⁹, R¹⁷ and R¹⁸ are each subject to the corresponding exemplifying observations above.

Preference is given to using in the process according to the invention a substrate on which there are one or more azo dyes of the formula I where

R¹, R² and R³ are each independently of the others hydrogen, alkyl or alkoxyalkyl, each of which may have up to 15 carbon atoms and be substituted by phenyl, C₁ -C₄ -alkylphenyl, C₁ -C₄ -alkoxyphenyl or cyano, or a radical of the formula III

    [--(CH.sub.2).sub.3 --O].sub.p [--CH.sub.2 --CH.sub.2 --O]--R.sup.5 (III),

where

n is 1, 2, 3 or 4,

p is 0 or 1 and

R⁵ is C₁ -C₄ -alkyl or phenyl, and R⁴ is methyl.

Particular preference is given to the novel process using a substrate on which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formula IVa, IVb, IVd or IVf where R⁷, R⁸ and R⁹ are each independently of the others alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, which may each have up to 10 carbon atoms, hydrogen, cyano, halogen, nitro or a radical of the formula --CO--OR¹⁹, --CO--NR¹⁹ R²⁰, --SO₂ --R¹⁹, --SO₂ --OR¹⁹ or SO₂ --NR¹⁹ R²⁰ where R¹⁹ and R²⁰ are each independently of the other alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, which may each have up to 10 carbon atoms, hydrogen or a radical of the formula 1

    [                                                          (II),

where R⁵ and n are each as defined above.

Particular preference is further given to the novel process using a substrate in which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formula IVc where

R¹⁰ is hydrogen, chlorine, C₁ -C₈ -alkyl, unsubstituted C₁ -C₄ -alkyl- or C₁ -C₄ -alkoxy-substituted phenyl or benzyl,

R¹¹ is cyano or a radical of the formula --CO--OR¹⁹ or --CO--NR¹⁹ R²⁰ where R¹⁹ and R²⁰ are each as defined above, and

R¹² is a radical of the formula ##STR6## where R¹⁹ and R²⁰ are each as defined above.

Preference is further given to the novel process using a substrate on which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formula IVe where

R¹⁰ is hydrogen, chlorine, C₁ -C₈ -alkyl, unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄ -alkkoxy-substituted phenyl or benzyl and

R¹² is cyano, nitro, formyl or a radical of the formula --CO--OR¹⁹ where R¹⁹ is as defined above.

Preference is further given to the novel process using a substrate on which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formual IVg where

R¹⁰ is C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, alkoxyalkyl, of up to 8 carbon atoms, unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄ -alkoxy-substituted phneyl, benzyl or benzyloxy and

R¹¹ is cyano, nitro or a radical of the formula --CO--OR¹⁹ where R¹⁹ is as defined above.

Preference is furter given to the novel process using a substrate on which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formula IVc where

R¹⁰ is hydrogen, chlorine, C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, alkoxyalkyl of up to 8 carbon atoms, unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄ -alkoxy-substituted phneyl, benzyl or a radical of the formula --CO--OR¹⁹ where R¹⁹ is as defined above,

R¹¹ is cyano or a radical of the formula --CO--OR¹⁹ where R¹⁹ is as defined above, and

R¹² is cyano, nitro, formyl or a radical of the formula --CO--OR¹⁹ where R¹⁹ is as defined above.

Particularly good results are obtained on using a substrate on which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formula IVa, IVb, IVc, IVd, IVe, IVf or IVg where R¹⁹ and (if present) R²⁰ are each hydrogen or C₁ -C₅ -alkyl.

Particularly favorable results are further obtained on using a substrate on which there are one or more azo dyes of the formula I where the radical D is derived from a diazo component conforming to the formula V ##STR7## where R⁷ is as defined above.

The dyes of the formula I are known per se or can be obtained by methods known per se.

Compared with the dyes used in existing processes, the dyes transferred in the process according to the invention are notable in general for improved migration properties in the receiving medium at room temperature, more ready thermal transferability, higher photochemical stability, easier industrial accessibility, better resistance to moisture and chemical substances, higher color strength, better solubility, higher purity of hue and in particular by substantially higher light fastness.

It is further surprising that the dyes of the formula I are readily transferable despite their relatively high molecular weight.

To prepare the dye substrate required for the novel process, the dyes are incorporated in a suitable organic solvent, for example chlorobenzene, isobutanol, methyl ethyl ketone, methylene chloride, toluene, tetrahydrofuran or a mixture thereof, with one or more binders with or without assistants to give a printing ink. This ink preferably contains the dye in a molecularly dispersed, ie. dissolved, form. The printing ink is applied to the inert substrate by knife coating and dried in air. Suitable binders are all resins or polymer materials which are soluble in organic solvents and are capable of holding the dye on the inert substrate in an abrasion-resistant bond. Preference is given to binders which, after the printing ink has dried in air, hold the dye in a clear, transparent film without visible crystallization of the dye.

Examples of such binders are cellulose derivatives, for example methylcellulose, ethylcellulose, ethylhydroxyethylcellulose, hydroxypropylcellulose, cellulose acetate or cellulose acetobutyrate, starch, alginates, alkyd resins, vinyl resins, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyrate or polyvinylpyrrolidones. Other possibilities as binders are polymers and copolymers of acrylates or derivatives thereof, such as polyacrylic acid, polymethyl methacrylate or styrene/acrylate copolymers, polyester resins, polyamide resins, polyurethane resins or natural CH resins, such as gum arabic. Further suitable binders are described in DE-A-3,524,519.

Preferred binders are ethylcellulose and ethylhydroxyethylcellulose.

The ratio of binder to dye preferably varies from 5:1 to 1:1.

Possible assistants are release agents as described in EP-A-227,092, EP-A-192,435 and the patent applications cited therein and also particularly organic additives which stop the transfer dye from crystallizing in the course of storage or heating of the inked ribbon, for example cholesterol or vanillin.

Inert substrates are for example tissue, blotting or parchment paper or plastics films of high heat stability, for example uncoated or metal-coated polyester, polyamide or polyimide. The inert substrate may additionally be coated on the side facing the thermal printing head with a lubricant, or slipping, layer in order to prevent adhesion of the thermal printing head to the substrate material. Suitable lubricants are described for example in EP-A-216,483 and EP-A-277,095. The thickness of the dye substrate is in general from 3 to 30 μm, preferably from 5 to 10 μm.

Suitable dye receiver layers are basically all temperature stable plastics layers having an affinity for the dyes to be transferred whose glass transition temperature should- preferably be in the temperature range 50° C. <Tg <100° C. Examples are modified polycarbonates or polyesters. Suitable recipes for the receiver layer composition are described in detail for example in EP-A-227,094, EP-A-133,012, EP-A-133,011, EP-A-111,004, JP-A-199,997/1986, JP-A-283,595/1986, JP-A-237,694/1986 and JP-A-127,392/1986.

Transfer is effected by means of a thermal printing head which must be heatable to a temperature ≧300° C. for the dye transfer to take place within the time interval t: 0 <t <15 msec. On heating, the dye migrates out of the transfer sheet and diffuses into the surface coating of the receiving medium.

Details of the preparation may be found in the Examples, where percentages are by weight, unless otherwise stated.

Transfer of dyes

To be able to test the transfer characteristics of the dyes in a quantitative and simple manner, the thermotransfer was carried out with large hotplates instead of a thermal printing head, with the transfer temperature being varied within the range 70° C. <T <120° C. and the transfer time being set at 2 minutes.

(A) General recipe for coating the substrate with dye:

X g of binder are dissolved at from 40° to 50° C. in 8 ml of 8:2 v/v toluene/ethanol. A solution of 0.25 g of dye (and any cholesterol as assistant) in 5 ml of tetrahydrofuran was added by stirring. The print paste thus obtained was smoothed down with an 80 μm knife on a sheet of polyester film (thickness: 6-10 μm) and dried with a hair dryer. (The weight ratio of dye:binder:assistant, from which the absolute amount of binder and assistant can be derived, is given for each case in the tables.)

(B) Testing of thermal transferability

The dyes used were tested in the following manner:

The polyester sheet donor containing the dye under test on the coated front was placed face down on commercial Hitachi Color Video Print Paper (receiver) and pressed down. Donor/receiver were then wrapped in aluminum foil and heated between two hotplates at different temperatures T (within the temperature range 70° C. <T <120° C.). The amount of dye diffusing into the bright plastics layer of the receiver is proportional to the optical density (=absorbance A). The latter was determined photometrically. If the logarithm of the absorbance A of the colored receiver papers measured within the temperature range from 80°to 110° C. is plotted against the corresponding reciprocal absolute-temperature, the result is a straight line whose slope gives the activation energy ΔE_(T) for the transfer experiment: ##EQU1##

To complete the characterization, the plots additionally reveal the temperature T*[° C.] at which the absorbance A of the dyed receiver papers attains the value 2.

The dyes mentioned in the Tables below were processed according to (A), and the resulting dye-coated substrates were tested in respect of their transfer characteristics by (B). The Tables list in each case the thermotransfer parameters T* and ΔE_(T), the absorption maximum of the dyes λ_(max) (measured in methylene chloride), the binders used and the weight ratio of dye: binder:assistant.

The abbreviations have the following meanings: B =binder (EC=ethylcellulose, EHEC=ethylhydroxyethylcellulose, ethylcellulose, AC =cellulose acetobutyrate, MIX mixture of polyvinyl butyrate and ethylcellulose in a weight ratio of 2:1)

D =dye

Chol =cholesterol (assistant)

                                      TABLE 1                                      __________________________________________________________________________      ##STR8##                                                                       No.Example                                                                          R.sup.1                                                                              R.sup.2    R.sup.3     [nm]λmax                                                                    B   Chol.                                                                              D:B:Chol.                                                                            [°C.                                                                       ##STR9##               __________________________________________________________________________     1    C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 C.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          544 EC  -   1:4   106                                                                               17                      2    C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          543 EC  -   1:4   109                                                                               14                      3    C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OCH.sub.3                                                                  544 EHE -   1:4   105                                                                               12                      4    C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OCH.sub.3                                                                  544 AC  -   1:4   110                                                                               16                      5    C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OCH.sub.3                                                                      EC  -   1:3    96                                                                               24                      6    C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          543 EHEC                                                                               -   1:4   109                                                                               13                      7    C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          543 EC  +   1:4:0.75                                                                              92                                                                               25                      8    C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          543 EC  -   1:2    91                                                                               24                      9    H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.2                             H.sub.5     532 EC  -   1:4   113                                                                               21                      10   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                       C.sub.6 H.sub.5                                                                            547 EC  +   1:4:0.75                                                                             111                                                                               25                      11   H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                        533 EC  +   1:4:0.75                                                                              93                                                                               19                      12   H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                        533 EHEC                                                                               +   1:4:0.75                                                                              90                                                                               28                      13   H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                          534 EC  +   1:4:0.75                                                                              96                                                                               23                      14   H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                          534 EHEC                                                                               +   1:4:0.75                                                                              92                                                                               31                      15   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4 H.sub.9                                C.sub.3 H.sub.6 OCH.sub.3                                                                  535 EC  -   1:2    95                                                                               31                      16   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4 H.sub.9                                C.sub.3 H.sub.6 OCH.sub.3                                                                  535 EC  -   1:4   101                                                                               24                      17   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4 H.sub.9                                C.sub.3 H.sub.6 OCH.sub.3                                                                  535 EC  +   1:4:0.75                                                                              95                                                                               24                      18   H     C.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                          C.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                           530 EC  +   1:4:0.75                                                                             102                                                                               21                      19   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6OCOCH.sub.3                                                                 528 EC  +   1:4   130                                                                               20                      20   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                         C.sub.2 H.sub.5                                                                            530 EC  +   1:5:0.75                         21   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.2 H.sub.4 OCH.sub.3                                                                  541 EC  +   1:4:0.75                                                                              97                                                                               25                      22   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                         C.sub.3 H.sub.6 OCH.sub.3                                                                  534 EC  +   1:4:0.5                                                                               88                                                                               20                      23   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                         C.sub.3 H.sub.6 OCH.sub.3                                                                  534 EC  +   1:4:0.75                                                                              88                                                                               32                      24   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                         C.sub.3 H.sub.6 OCH.sub.3                                                                  534 EC  +   1:4:1.0                                                                               85                                                                               25                      25   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                         C.sub.3 H.sub.6 OCH.sub.3                                                                  534 EC  -   1:4    94                                                                               20                      26   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4 H.sub.9                                C.sub.5 H.sub.10 CN                                                                        532 EC  -   1:4   100                                                                               23                      27   H     C.sub.4 H.sub.9                                                                           C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          534 EC  -   1:4   127                                                                               11                      28   C.sub.2 H.sub.5                                                                      C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          545 MIX -   1:4   119                                                                               18                      29   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OCOCH.sub.3                                                                541 MIX -   1:4   107                                                                               9.0                     __________________________________________________________________________

                                      TABLE 2                                      __________________________________________________________________________      ##STR10##                                                                      No.Example                                                                          R.sup.1                                                                              R.sup.2    R.sup.3     [nm]λmax                                                                    B   Chol.                                                                              D:B:Chol.                                                                            [°C.                                                                       ##STR11##              __________________________________________________________________________     30   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C(CH.sub.3).sub.2 C.sub.2 H.sub.5                                                          534 EC  +   1:4:0.75                                                                             100                                                                               32                      31   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.2 H.sub.4 OCH.sub.3                                                                  534 EC  +   1:4:0.75                                                                             104                                                                               26                      32   H                                                                                     ##STR12##                                                                                 ##STR13##  530 EC  +   1:4:0.75                                                                             101                                                                               29                      33   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           (CH.sub.2).sub.3 OCH.sub.3                                                                 536 EC  +   1:4:0.75                                                                              97                                                                               27                      34   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OCOCH.sub.3                                                                534 EC  +   1:4:0.75                                                                              94                                                                               23                      35   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          534 EC  -   1:4   110                                                                               26                      36   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          534 EHE -   1:4   104                                                                               17                      37   H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                          532 EC  -   1:4   115                                                                               19                      38   H     C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4                             H.sub.9     532 EC  -   1:4   110                                                                               25                      39   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                         H           515 EC  +   1:4:0.75                                                                             115                                                                               21                      40   H     C.sub.2 H.sub.6 OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                         H           514 EC  +   1:4:0.75                                                                             109                                                                               31                      41   H     C.sub.3 H.sub.6 OC.sub.4 H.sub.8 OC.sub.4 H.sub.9                                         H           515 EC  +   1:4:0.75                                                                             106                                                                               32                      42   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                                H           515 EC  +   1:4:0.75                                                                             108                                                                               30                      43   H     C.sub.3 H.sub.6 OC.sub.4 H.sub.8 OC.sub.2 H.sub.5                                         H           515 EC  +   1:4:0.75                                                                             106                                                                               30                      44   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          537 EC  +   1:4:0.75                                                                              98                                                                               21                      45   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                           534 EC  -   1:4   113                                                                               24                      46   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4                                        H.sub.9     513 EC  -   1:4   113                                                                               27                      47   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          536 EC  -   1:4   112                                                                               19                      48   C.sub.2 H.sub.5                                                                      C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 OCH.sub.3                                                                  537 MIX -   1:4   105                                                                               13                      49   C.sub.2 H.sub.5                                                                      C.sub.3 H.sub.6 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          537 EC  -   1:4    98                                                                               20                      __________________________________________________________________________

                                      TABLE 3                                      __________________________________________________________________________      ##STR14##                                                                      No.Example                                                                          R.sup.1                                                                           R.sup.2                                                                           R.sup.3                                                                               [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol:                                                                            [°C.]T*                                                                    ##STR15##                               __________________________________________________________________________     50   C.sub.2 H.sub.5                                                                   C.sub.2 H.sub.5                                                                   C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                      522 EC +   1:4:0.75                                                                             92 28                                       __________________________________________________________________________

                                      TABLE 4                                      __________________________________________________________________________      ##STR16##                                                                      No.Example                                                                          R.sup.1                                                                           R.sup.2   R.sup.3   [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR17##                     __________________________________________________________________________     51   C.sub.2 H.sub.5                                                                   C.sub.2 H.sub.5                                                                          C.sub.3 H.sub.6 OCH.sub.3                                                                522 EC +   1:4:0.75                                                                              84                                                                               21                             52   H  C.sub.6 H.sub.5                                                                          C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               524 EC +   1:4:0.75                                                                             100                                                                               32                             53   H                                                                                  ##STR18##                                                                               C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               532 EC +   1:4:0.75                                                                              93                                                                               22                             54   H  C.sub.3 H.sub.6 OC.sub.4 H.sub.8 OC.sub.2 H.sub.5                                        H         494 EC +   1:4:0.75                                                                              90                                                                               21                             __________________________________________________________________________

                                      TABLE 5                                      __________________________________________________________________________      ##STR19##                                                                      No.Example                                                                          R.sup.1                                                                              R.sup.2    R.sup.3     [nm]λmax                                                                    B   Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR20##              __________________________________________________________________________     55   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                          527 EC  +   1:2:0.75                                                                             100                                                                               30                      56   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                           526 EC  +   1:2:0.75                                                                              91                                                                               29                      57   H     C.sub.6 H.sub.5                                                                           C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                        527 EC  +   1:4:0.75                                                                             116                                                                               24                      58   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                  ##STR21##  527 EC  +   1:4:0.75                                                                             108                                                                               27                      59   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                       C.sub.6 H.sub.5                                                                            528 EC  -   1:4   127                                                                               20                      __________________________________________________________________________

                                      TABLE 6                                      __________________________________________________________________________      ##STR22##                                                                      ##STR23##                                                                            R.sup.1                                                                           R.sup.2       R.sup.3                                                                                   ##STR24##                                                                           B  Chol.                                                                               D:B:Chol.                                                                            ##STR25##                                                                         ##STR26##             __________________________________________________________________________     60    H  C.sub.6 H.sub.5                                                                              C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2                                     CH.sub.3   557  EC +    1:2:0.75                                                                             107                                                                               22                     61    H  C.sub.3 H.sub.6 OCHCH.sub.3 CH.sub.2 OCH.sub.3                                               H          537  EC +    1:4:0.75                                                                             101                                                                               30                     62    H  C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                            H          534  EC +    1:4:0.75                                                                              95                                                                               23                     63    H  C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                            H          537  EC +    1:4:0.75                                                                             107                                                                               29                     64    C.sub.3 H.sub.7                                                                   C.sub.3 H.sub.7                                                                              C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                         565  EC -    1:4   106                                                                               20                     65    H  CH.sub.2 CH.sub.2 OCOCH.sub.3                                                                C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                         547  MIX                                                                               -    1:4   116                                                                               14                     __________________________________________________________________________

                                      TABLE 7                                      __________________________________________________________________________      ##STR27##                                                                      ##STR28##                                                                           R.sup.1                                                                          R.sup.2   R.sup.3                                                                          ##STR29##                                                                          B  Chol.                                                                              D:B:Chol.                                                                            ##STR30##                                                                         ##STR31##                              __________________________________________________________________________     66   H C.sub.3 H.sub.6 OC.sub.4 H.sub.8 OC.sub.4 H.sub.9                                        H 515 EC +   1:4:0.75                                                                             102                                                                               24                                      67   H C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                        H 514 EC +   1:4:0.75                                                                             100                                                                               32                                      __________________________________________________________________________

                                      TABLE 8                                      __________________________________________________________________________      ##STR32##                                                                      ##STR33##                                                                           R.sup.1                                                                          R.sup.2   R.sup.3                                                                                  ##STR34##                                                                          B  Chol.                                                                              D:B:Chol.                                                                            ##STR35##                                                                         ##STR36##                      __________________________________________________________________________     68   H C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                        C.sub.2 H.sub.5                                                                          519 EC +   1:4:0.75                                                                             97 26                              69   H C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                        C.sub.3 H.sub.6 OC.sub.4 H.sub.8 OC.sub.4 H.sub.9                                        526 EC +   1:4:0.75                                                                             96 24                              __________________________________________________________________________

                                      TABLE 9                                      __________________________________________________________________________      ##STR37##                                                                      ##STR38##                                                                           R.sup.1                                                                              R.sup.2                                                                              R.sup.3                                                                                  ##STR39##                                                                          B  Chol.                                                                              D:B:Chol.                                                                            ##STR40##                                                                         ##STR41##                      __________________________________________________________________________     70   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OCH.sub.3                                                                534 EC -   1:4   112                                                                               24                              71   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub. 3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                       534 EC -   1:4   112                                                                               24                              __________________________________________________________________________

                                      TABLE 10                                     __________________________________________________________________________      ##STR42##                                                                      ##STR43##                                                                           R.sup.1                                                                           R.sup.2   R.sup.3                                                                                  ##STR44##                                                                          B  Chol.                                                                              D:B:Chol.                                                                            ##STR45##                                                                         ##STR46##                     __________________________________________________________________________     72   H  C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                        H         520 EC +   1:4:0.75                                                                             98 20                             73   C.sub.2 H.sub.5                                                                   C.sub.2 H.sub.5                                                                          C.sub.3 H.sub.6 OC.sub. 4 H.sub.8 OC.sub.4 H.sub.9                                       545 EC +   1:4:0.75                                                                             96 25                             __________________________________________________________________________

                                      TABLE 11                                     __________________________________________________________________________      ##STR47##                                                                      ##STR48##                                                                           R.sup.1                                                                          R.sup.2    R.sup.3                                                                                   ##STR49##                                                                          B  Chol.                                                                              D:B:Chol.                                                                            ##STR50##                                                                         ##STR51##                    __________________________________________________________________________     74   H CH(C.sub.2 H.sub.5)CH.sub.2 OCH.sub.3                                                     CH(C.sub.2 H.sub.5)CH.sub.2 OCH.sub.3                                                     502 EC +   1:4:0.75                                                                              95                                                                               22                            75   H CH(C.sub.2 H.sub.5)CH.sub.2 OCH.sub.3                                                     CH(CH.sub.3).sub.2                                                                        503 EC +   1:4:0.75                                                                             100                                                                               24                            __________________________________________________________________________

                                      TABLE 12                                     __________________________________________________________________________      ##STR52##                                                                      ##STR53##                                                                           R.sup.1                                                                          R.sup.2                                                                           R.sup.3                                                                                  ##STR54##                                                                          B  Chol.                                                                              D:B:Chol.                                                                            ##STR55##                                                                         ##STR56##                             __________________________________________________________________________     76   H C.sub.6 H.sub.5                                                                   C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               442 EC -   1:4   107                                                                               26                                     __________________________________________________________________________

                                      TABLE 13                                     __________________________________________________________________________      ##STR57##                                                                                                                            /                                                                                R.sup.1#                                                                     R.sup.2  R.sup.3                                                                 BS Chol.                                                                     D:B:Chol.                                                                       ##STR60##                                                                      ##STR61##              __________________________________________________________________________     77    C.sub.2 H.sub.4 OCH.sub.3                                                                C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                      619  EC +   1:4:0.75                                                                             100                                                                               29                      78    C.sub.2 H.sub.4 OCH.sub.3                                                                C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub. 3 H.sub.6 OCH.sub.3                                                            619  EC +   1:4:0.75                                                                             110                                                                               26                      79    C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                        C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                         C.sub.3 H.sub.6 OCH.sub.3                                                             618  EC -   1:4   123                                                                               17                      __________________________________________________________________________

                                      TABLE 14                                     __________________________________________________________________________      ##STR62##                                                                      Example No.                                                                         R.sup.1                                                                              R.sup.2    R.sup.3                                                                               λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [°C.]                                                                   ##STR63##                    __________________________________________________________________________     80   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.2 H.sub.4 OCH.sub.3                                                             508 EC +   1:4:0.75                                                                              94                                                                               31                            81   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                      515 EC -   1:2    86                                                                               28                            82   C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                           C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                      515 EC +   1:4:0.75                                                                              93                                                                               30                            83   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OCH.sub.3                                                             508 EC -   1:2    89                                                                               17                            84   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                 C.sub.3 H.sub.6 OCH.sub.3                                                             508 EC +   1:4:0.75                                                                              95                                                                               25                            85   H     C.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                          C.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                      505 EC -   1:4   109                                                                               30                            86   H     C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                         C.sub.3 H.sub.6 OCH.sub.3                                                             504 EC -   1:4   103                                                                               26                            87   H     C.sub.3 H.sub.6 O(C.sub.2 H.sub.4 O).sub.2 C.sub.4 H.sub.9                                C.sub.3 H.sub.6 OCH.sub.3                                                             497 EC -   1:4   105                                                                               30                            __________________________________________________________________________

                                      TABLE 15                                     __________________________________________________________________________      ##STR64##                                                                      Example No.                                                                         R.sup.1                                                                            R.sup.2                                                                            R.sup.3  λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [°C.]                                                                   ##STR65##                           __________________________________________________________________________     88   C.sub.2 H.sub.5                                                                    C.sub.2 H.sub.5                                                                    C.sub.3 H.sub.6 O.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        548 EC -   1:4   123                                                                               15                                   __________________________________________________________________________

                                      TABLE 16                                     __________________________________________________________________________      ##STR66##                                                                      Example No.                                                                         R.sup.1                                                                              R.sup.2                                                                              R.sup.3                                                                               λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [°C.]                                                                   ##STR67##                         __________________________________________________________________________     89   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OCH.sub.3                                                             555 EC -   1:4   110                                                                               23                                 90   C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                      558 EC -   1:4   111                                                                               18                                 __________________________________________________________________________

                                      TABLE 17                                     __________________________________________________________________________      ##STR68##                                                                      Example No.                                                                         R.sup.1                                                                            R.sup.2                                                                            R.sup.3   λmax [nm]                                                                   B  Chol.                                                                             D:B:Chol.                                                                            T* [°C.]                                                                    ##STR69##                          __________________________________________________________________________     91   C.sub.2 H.sub.5                                                                    C.sub.2 H.sub.5                                                                    C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                         614 EC -   1:4  104 35                                  92   C.sub.2 H.sub.5                                                                    C.sub.2 H.sub.5                                                                    C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        615 EC -   1:4  100 25                                  93   C.sub.2 H.sub.5                                                                    C.sub.2 H.sub.5                                                                    (CH.sub.2).sub.4 OC.sub.4 H.sub.9                                                        614 EC -   1:4  108 24                                  94   C.sub.3 H.sub.7                                                                    C.sub.3 H.sub.7                                                                    C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        618 MIX                                                                               -   1:4  118 13                                  95   C.sub.3 H.sub.7                                                                    C.sub.3 H.sub.7                                                                    C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        618 EC -   1:4  100 30                                  __________________________________________________________________________

                                      TABLE 18                                     __________________________________________________________________________      ##STR70##                                                                      Example No.                                                                         X   R.sup.1                                                                            R.sup.2                                                                            R.sup.3   λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [°C.]                                                                   ##STR71##                      __________________________________________________________________________     96   C.sub.4 H.sub.9                                                                    C.sub.2 H.sub.5                                                                    C.sub.2 H.sub.5                                                                    C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                         598 EC -   1:4   117                                                                               28                              97   C.sub.4 H.sub.9                                                                    C.sub.3 H.sub.7                                                                    C.sub. 3 H.sub.7                                                                   C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        601 EC -   1:4   127                                                                               16                              __________________________________________________________________________

                                      TABLE 19                                     __________________________________________________________________________      ##STR72##                                                                      Example No.                                                                         R.sup.1                                                                              R.sup.2                                                                              R.sup.3   λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [A = 1] [°C.]                                                              ##STR73##                   __________________________________________________________________________      98  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OH.sub.3                                                                 601 EC -   1:4   127   16                            99  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        601 EC -   1:4   129   15                           100  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        607 EC -   1:4   124   15                           101  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.4 H.sub.9                                                                          605 EC +   1:4:0,75                                                                              98   21                           __________________________________________________________________________

                                      TABLE 20                                     __________________________________________________________________________      ##STR74##                                                                      Example No.                                                                         R.sup.1                                                                              R.sup.2   R.sup.3   λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [°C.]                                                                   ##STR75##                  __________________________________________________________________________     102  C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                          C.sub.3 H.sub.6 OCH.sub.3                                                                517 EC +   1:4:0.75                                                                              84                                                                               15                          103  C.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                                                          C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        518 EC +   1:4:0.75                                                                              87                                                                               20                          104  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                                C.sub.2 H.sub.4 OCH.sub.3                                                                504 EC +   1:4:0.75                                                                              97                                                                               22                          105  H     C.sub.2 H.sub.4 OCONHC.sub.4 H.sub.9                                                     C.sub.2 H.sub.5                                                                          501 EC +   1:4:0.75                                                                             111                                                                               24                          __________________________________________________________________________

                                      TABLE 21                                     __________________________________________________________________________      ##STR76##                                                                      Example No.                                                                         R.sup.1                                                                            R.sup.2                                                                            R.sup.3   λmax [nm]                                                                   B  Chol.                                                                              D:B:Chol.                                                                            T* [°C.]                                                                   ##STR77##                          __________________________________________________________________________     106  C.sub.2 H.sub.5                                                                    C.sub.2 H.sub.5                                                                    C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        531 EC -   1:4   107                                                                               16                                  __________________________________________________________________________

                                      TABLE 22                                     __________________________________________________________________________      ##STR78##                                                                      No.Example                                                                          R.sup.1                                                                           R.sup.2                                                                           R.sup.3                                                                              [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR79##                                __________________________________________________________________________     107  C.sub.2 H.sub.5                                                                   C.sub.2 H.sub.5                                                                   C.sub.3 H.sub.6 OCH.sub.3                                                            555 EC -   1:4   118                                                                               16                                        __________________________________________________________________________

                                      TABLE 23                                     __________________________________________________________________________      ##STR80##                                                                      No.Example                                                                          R.sup.1                                                                          R.sup.2                                                                               R.sup.3   [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR81##                         __________________________________________________________________________     108  H                                                                                 ##STR82##                                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               532 EC -   1:4   102                                                                               15                                 __________________________________________________________________________

                                      TABLE 24                                     __________________________________________________________________________      ##STR83##                                                                      No.Example                                                                          R.sup.1                                                                              R.sup.2                                                                              R.sup.3   [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR84##                      __________________________________________________________________________     109  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        535 MIX                                                                               -   1:4   87 21                              110  C.sub.2 H.sub.5                                                                      C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        537 MIX                                                                               -   1:4   91 19                              __________________________________________________________________________

                                      TABLE 25                                     __________________________________________________________________________      ##STR85##                                                                      No.Example                                                                          R.sup.1                                                                           R.sup.2                                                                           R.sup.3   R.sup.10                                                                          [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR86##                         __________________________________________________________________________     111  C.sub.2 H.sub.5                                                                   C.sub.2 H.sub.5                                                                   C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        H  595 MIX                                                                               -   1:4   118                                                                               16                                 112  C.sub.2 H.sub. 5                                                                  C.sub.2 H.sub.5                                                                   C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        CH.sub.3                                                                          598 MIX                                                                               -   1:4   122                                                                               14                                 __________________________________________________________________________

                                      TABLE 26                                     __________________________________________________________________________      ##STR87##                                                                      No.Example                                                                          R.sup.1                                                                          R.sup.2   R.sup.3                                                                           R.sup.13                                                                          R.sup.14                                                                          [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR88##                       __________________________________________________________________________     123  H C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               C.sub.6 H.sub.5                                                                   H  H  495 EC +   1:4:0.75                                                                             113                                                                               32                               __________________________________________________________________________

                                      TABLE 27                                     __________________________________________________________________________      ##STR89##                                                                      No.Example                                                                          R.sup.1                                                                          R.sup.2   R.sup.3   R.sup.10                                                                          [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR90##                   __________________________________________________________________________     114  H C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        CH.sub.3                                                                          540 MIX                                                                               -   1:4   109                                                                               14                           __________________________________________________________________________

                                      TABLE 28                                     __________________________________________________________________________      ##STR91##                                                                      No.Example                                                                          R.sup.1                                                                          R.sup.2   R.sup.3   [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR92##                      __________________________________________________________________________     115  H C.sub.3 H.sub.6 OCH(CH.sub.3).sub.2                                                      C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        544 MIX                                                                               -   1:4   107                                                                               20                              116  H C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OCH.sub.3                                               C.sub.3 H.sub.6 OC.sub.2 H.sub.4 OC.sub.                                                 544.sub.5                                                                          MIX                                                                               -   1:4   106                                                                               17                              __________________________________________________________________________

                                      TABLE 29                                     __________________________________________________________________________      ##STR93##                                                                      No.Example                                                                          R.sup.1                                                                              R.sup.2                                                                              R.sup.3                                                                               [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR94##                         __________________________________________________________________________     117  C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.3 H.sub.6 OC.sub.2 H.sub.5                                                      601 EC -   1:4   126                                                                               17                                 __________________________________________________________________________

                                      TABLE 30                                     __________________________________________________________________________      ##STR95##                                                                      No.Example                                                                          R.sup.1                                                                          R.sup.2                                                                              R.sup.3                                                                              R         [nm]λmax                                                                    B  Chol.                                                                              D:B:Chol.                                                                            [°C.]T*                                                                    ##STR96##                    __________________________________________________________________________     118  H C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        511 EC -   1:4   121                                                                               17                            119  H C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.3                                                            C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OC.sub.6 H.sub.5                                        510 EC -   1:4   108                                                                               24                            120  H C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.2 H.sub.4 OC.sub.3 H.sub.7                                                         520 EC -   1:4   113                                                                               24                            121  H C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.2 H.sub.4 OCH.sub.2 C.sub.6 H.sub.5                                                521 EC +   1:4:0.75                                                                             102                                                                               29                            122  H C.sub.3 H.sub.6 OCH.sub.3                                                            C.sub.3 H.sub.6 OCH.sub.3                                                            CH.sub.2 OCH.sub.3                                                                       523 EC +   1:4:0.75                                                                             121                                                                               15                            __________________________________________________________________________ 

We claim:
 1. A process for transferring azo dyes from a substrate to a plastic-coated paper by diffusion with the aid of a thermal printing head, which comprises using a substrate on which there are one or more azo dyes of the formula I ##STR97## where R¹, R² and R³ are identical or different and each is independently of the other (a) alkyl, alkoxyalkyl, alkanoyloxyalkyl, alkoxycarbonyloxyalkyl or alkoxycarbonylalkyl, each having up to 20 carbon atoms and being unsubstituted or substituted by phenyl, C₁ -C₄ -alkylphenyl, C₁ -C₄ -alkoxyphenyl, halophenyl, benzyloxy, C₁ -C₄ -alkylbenzyloxy, C₁ -C₄ -alkoxylbenzyloxy, halobenzyloxy, halogen, hydroxyl or cyano, (b) hydrogen, (c) unsubstituted or C₁ -C₁₅ -alkyl-, C₁ -C₁₅ -alkoxy-, halogen- or benzyloxy-substituted phenyl, (d) unsubstituted or C₁ -C₁₅ -alkyl-, C₁ -C₁₅ -alkoxy-, halogen- or benzyloxy-substituted benzyl or (e) a radical of the formula II

    (--Y--O).sub.m -R.sup.5                                    (II)

whereY is C₂ -C₆ -alkylene, m is 1, 2, 3, 4, 5 and 6 and R⁵ is C₁ -C₄ -alkyl or unsubstituted or C₁ -C₄ -alkyl-or C₁ -C₄ -alkoxy-substituted phenyl, R⁴ is C₁ -C₄ -alkyl and D is the radical of a diazo component of the formula ##STR98## where R⁷, R⁸ and R⁹ are identical or different and each is independently or the other (a) alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, each having up to 12 carbon atoms, (b) hydrogen, (d) cyano, (d) halogen, (e) nitro, or (f) a radical of the formula

    (--Y--O).sub.m -R.sup.5

where Y, R⁵ and m are each as defined above, or Y or R⁵ are a radical of the formula --CO--OR¹⁷, --CO--NR¹⁷ R¹⁸, --SO₂ --R¹⁷, --SO₂ --OR¹⁷ or --SO₂ --NR¹⁷ R¹⁸, where R¹⁷ are R¹⁸ are identical or different and each is independently of the other (a) alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, each having up to 12 carbon atoms, (b) hydrogen or (c) a radical of the formula

    (--Y--O).sub.m -R.sup.5

where Y, R⁵ and m are each as defined above, R¹⁰ is hydrogen, chlorine, cyano, C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, C₁ -C₈ -alkylthio, alkoxyalkyl of up to 8 carbon atoms, phenyl unsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or benzyloxy, benzyl, benzyloxy or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above, R¹¹ is hydrogen, cyano, nitro or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above, R¹² is cyano, nitro, formyl or a radical of the formula ##STR99## where R¹⁷ and R¹⁸ are each as defined above, R¹³ and R¹⁴ are identical or different and each is independently of the other hydrogen, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, chlorine, cyano, nitro or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above, R¹⁵ is hydrogen, C₁ -C₄ -alkyl or chlorine, and R¹⁶ is cyano or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸ where R¹⁷ and R¹⁸ are each as defined above.
 2. A process as claimed in 1, wherein there are on the substrate used one or more azo dyes of formula I ##STR100## where R¹, R² and R³ are each independently of the others (a) hydrogen, (b) alkyl or alkoxyalkyl, each having up to 15 carbon atoms and being unsubstituted or substituted by phenyl, C₁ -C₄ -alkylphenyl, C₁ -C₄ -alkoxyphenyl or cyano, or (c) a radical of the formula III

    (--(CH.sub.2).sub.3 --O).sub.p (--CH.sub.2 --CH.sub.2 --O).sub.n --R.sup.6 (III)

wheren is 1, 2, 3 or 4, p is 0 or 1 and R⁶ is C₁ -C₄ -alkyl or phenyl, and R⁴ is methyl. 